JP4262108B2 - Network management system - Google Patents

Description

  The present invention specifies an explicit route from a source router to a destination router, such as RSVP (Resource Reservation Protocol) that guarantees the bandwidth used in a GMPLS (Generalized Multi-protocol Label Switching) network, for example. The present invention relates to a network management system that performs routing when performing path setting and performs subsequent path management.

A routing method using a control plane of each router based on the OSPF (Open Shortest Path First: (see Non-Patent Documents 1 and 2)) protocol will be described with reference to FIGS.
FIG. 10 is a diagram for explaining a routing method in the same area in OSPF. In FIG. 10, 101 to 105 are routers (R: Router), 201 is a designated router (DR), 301 is a backup designated router (BDR), and 401 to 411 are bi-directional between routers. Indicates a link.

  The router is a node for performing data packet routing processing. The designated router 201 also has a router function, but establishes an adjacency relationship with each of the routers 101 to 105 and 301 and exchanges link state information, thereby synchronizing link state information within the same area. Play an important role. The backup designated router 301 is a router that can establish an adjacency relationship with other routers when the designated router 201 fails. The links 401 to 411 are in both directions, and can have different link state information for each direction. The link state information is represented numerically according to conditions such as delay, throughput, and reliability, but it is desirable that the link state information be dynamically reflected according to the link usage frequency. Each router sends the link state information of the link connected to the router to the designated router 201, and the link state information of the link connected to the other router is obtained from the designated router so that it is the same in the routers in all the areas. Holds link state information.

When routing within an area, when the router as the starting point is designated as the destination router and receives a path setting request, the end point is determined by Dijkstra's algorithm from all the link state information held by the router. Find the shortest route to
On the other hand, FIG. 11 is a diagram for explaining a routing method over a plurality of areas in OSPF. In FIG. 11, 106 to 117 are routers, 202 to 205 are designated routers, 302 to 305 are backup designated routers, 412 to 451 are bidirectional links in each area, and 501 to 504 are area border routers (ABR: Area Border). Router), 601 to 604 indicate bidirectional links between areas.

  The area border routers 501 to 504 exchange link state information between areas and information on logical nodes (in the figure, logical Node A to logical Node D) as numerical values. Information exchanged between the area border routers is also shared by all the routers by obtaining from the designated routers 202 to 205 in each area.

  When routing between areas, when the router as the starting point is designated as the destination router and receives a path setting request, the link state information in the area held by the router to the area border router A route is determined and routing between logical nodes is performed based on link state information between areas and logical node state information. Routing in other areas is performed by area border routers in other areas.

J.Moy, “OSPF Version 2,” RFC 2328, April 1998.

OSPF (Open Shortest Path First), Internet <URL: http: //www.wakhok.ac.jp/~kida/semi/OSPF/>

  In routing by OSPF, it is necessary to secure a data band for exchanging link state information between routers in addition to a band in which the router transfers user data, and the load on the router increases. Moreover, since the same information is shared between routers, the absolute amount of information increases with the number of routers.

  In OSPF, it is necessary to run the Dijkstra algorithm every time a path is set to obtain the shortest path. However, the order of the Dijkstra calculation amount is O (L log () when N is the number of nodes and L is the number of links. N)), and there are concerns that a delay may occur if there are several path setting requests per second.

  In OSPF, routing is performed based on link state information, but there is a problem that the exchange function of the router cannot be considered in the link state information. In particular, a router that switches light wavelengths is very expensive, and not all wavelengths can be exchanged. In that case, routing may not be possible due to the exchange capability of the router.

  For example, FIG. 12 shows the routing in the area of the logical node A of FIG. 11. Here, it is assumed that a numerical value indicated by a fraction is assigned to each link. In that case, the route with the lowest cost of the link from the origin router 108 to the destination router 302 is the route indicated by the arrow in the figure. However, if the router 501 has insufficient wavelength switching capability, etc. The path cannot be set.

In addition, when restricted routing (Exclude, Mandatory, Preferred) is used, there is a limit to the range that can be restricted. Targets specified by these conditions include nodes such as links and routers.
The target specified by Exclude must not pass when selecting a route. Exclude designation can be used to realize a VPN in addition to being used for avoiding a failure location when a node, link, or the like fails.

The target specified in Mandatory must be passed when selecting a route. The Mandatory designation can be applied when a router with a high exchange capacity is designated, or in a section where the grouping effect is particularly high.
The target specified by Preferred is preferably passed when selecting a route. The Preferred designation may be applied when a Preferred section is designated as a method for dealing with temporary congestion.

  Exclude specification can be realized by removing the Exclude specification target from the candidates when the target of Exclude specification appears in the route selection assumption in Dijkstra's algorithm when deciding the routing by OSPF, but Mandatory specification, Preferred The designation is difficult to realize with OSPF. For example, when there are two or more objects designated by the Mandatory designation, it is not realized in OSPF that all the Mandatory objects to be passed first are calculated. In addition, even if it is realized, the calculation amount becomes enormous.

  The present invention has been made in consideration of such circumstances, minimizing the delay in routing without minimizing the load on the router and the network, minimizing the path setting block rate due to the node exchange capability, The purpose is to provide a network management system that enables routing for Mandatory and Preferred conditions.

In order to achieve the above-described object, the present invention provides a list holding means for holding a list of routes between a starting point and an ending point that can be considered in advance for all managed nodes, and a starting point, an ending point, and a routing constraint condition. A sub-network management system having path setting means that accepts a specified path setting request and extracts and returns an appropriate route satisfying the routing constraint condition from the list held in the list holding means is a hierarchical distributed type in is disposed, said cooperation between the sub-network management system, in a network management system for managing a path routing, each sub-network management system receives the request for generating the list of root extraction condition is specified, the Minimal cost between possible start and end points Each of the suitable routes is extracted, and for each node that passes through each of the extracted optimum routes, the other route is selected from the node through the link that is not adopted in the optimum route derived from the node, and the other route is transmitted at the lowest cost. A list creating means for extracting a sub-route obtained by adding a route to the node from the starting point of the optimum route to the node thereafter in a range satisfying the route extraction condition, and creating a list of routes to be held in the list holding means; It is characterized by doing.

Further, the present invention provides a list holding means for holding a list of routes between a starting point and an ending point that can be considered in advance for all nodes under management, and a path setting request in which the starting point, the ending point, and a routing constraint condition are specified. A sub-network management system having a path setting unit that accepts and extracts an appropriate route that satisfies the routing constraint condition from the list held in the list holding unit and returns the route. In a network management system that manages path routing in cooperation between management systems, each of the sub-network management systems accepts a request to create the list in which route extraction conditions are specified, and the possible starting and ending points Each optimal route with the lowest cost is extracted In both cases, for each node that passes through the extracted optimum route, for each link that is not adopted in the optimum route derived from the node, the node reaches the other node through the link at the lowest cost. the sub-route was added to after the route from the starting point of the optimal route to the node, wherein the extraction with the root extraction conditions are satisfied, that list means an ingredient Bei to create a list of routes to be held in the list holding means It is characterized by.

In the present invention, the routing information that is redundantly held by a plurality of routers is collectively held by the subnetwork management system, thereby reducing the absolute amount of the retained information and eliminating the exchange of link state information between the routers. , Reduce the load on the router.
In OSPF, Dijkstra's algorithm, which was calculated every time routing is not performed, and a route list with high priority is created by using a thread different from routing, thereby reducing the delay in routing, and in the route list. By retrying the path setting for the number of lists in the order from low to low, the number of cases where routing cannot be performed due to the router exchange capability is minimized.

  Furthermore, for restricted routing (Exclude, Mandatory (mandatory), Preferred), after extracting the route that includes the Mandatory target from the route list that is held in advance, Mandatory constraints are realized by cost comparison method Then, the Preferred constraint is realized by a method of extracting a route including a larger number of Preferred objects from a route list held in advance.

  According to the present invention, a network that minimizes a delay in routing, minimizes a path setting block rate due to a node exchange capability, and enables constraint-based routing even for Mandatory and Preferred conditions without imposing a load on the router and the network. A management system can be provided.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a system configuration diagram of this embodiment. An example of application to a GMPLS (Generalized Multi-Protocol Label Switching) router will be described.
In the figure, reference numerals 10a to 10j are GMPLS routers to be managed. Reference numerals 11a to 11i denote links between routers of the management target GMPLS network. Reference numerals 20a to 20j correspond to 10a to 10j, respectively, and are network element (NE) management systems for monitoring and controlling the corresponding routers. Reference numerals 21a to 21i denote management objects (links) respectively corresponding to the links 11a to 11i, and the system is managed in an upper GMPLS subnetwork management system (NMS). Reference numerals 22a to 22d denote management objects (LC: Link Connection) for managing link connections actually used as user paths in the links. For example, when the link is an optical fiber, the link connection corresponds to the wavelength used therein. Reference numerals 23a to 23c denote management objects (XC: Cross Connection) for managing the switching used in the user path in the GMPLS router to be managed. For example, a router that performs wavelength switching manages that a red wavelength is switched to a blue wavelength. Systemically, the cross-connect object is managed in the NE management system.

  30a to 30d are GMPLS sub-NMS (GSN: GMPLS Subnetwork). The GMPLS sub NMS 30a (GSN_i) holds pointers to the lower NE management systems 20a to 20e, link objects 21a to 21d, and link connection objects 22a and 22b. In addition, a management object (SNC: Subnetwork Connection) 31a for managing an end-to-end connection in 30a formed by the link connection 22a, the cross connection 23a, the link connection 22c, and the cross connection 23b is held. Similarly, the GMPLS sub NMS 30b (GSN_j) holds pointers to the lower NE management systems 20f, 20h, and 20i, link objects 21g and 21h, and link connection objects 22d, and the subnetwork formed by the cross connection 23c and the link connection 22d. The connection object 31b is held. The GMPLS sub NMS 30c (GSN_k) holds the pointers of the lower NE management systems 20g and 20j and the link object 21i. The GMPLS sub NMS 30d (TOP_GSN) holds pointers to the lower three GMPLS sub NMSs and link connection objects 22c in 21e, 21f, and 21e, which are link objects between the lower sub networks. Further, the subnetwork connection 31c which is an end-to-end connection in the GMPLS sub NMS 30d formed by the lower subnetwork connection 31a, the link connection 22c, and the lower subnetwork connection 31b is held.

  If the subnetwork connection 31c holds the starting point and the ending point of the path at both ends, the GMPLS sub NMS 30d also holds an end-to-end path object (trail object). The trail object holds customer information for the path such as path user information that the subnetwork connection object does not have.

  The manager system 40 makes a monitoring / control request to these hierarchically distributed NMSs. For monitoring, link and node configuration information and user path configuration information can be displayed in units of sub-networks. It is also possible to request link connection information in the link. Further, it is possible to acquire a failure of the router and the link from the GMPLS sub NMS together with the affected path. A new addition of a link and a new addition of a path are set by making a request to the GMPLS sub NMS in which the target link and path are accommodated.

The figure is merely an example, and the number of layers of the GMPLS sub-NMS, the number of sub-NMSs in the same layer, and the group unit of the subordinate sub-NMS / NE management system managed by the sub-NMS are arbitrary and there is no limitation.
FIG. 2 shows an example of managing a hierarchical route in a hierarchical distributed NMS. The GMPLS network shown in FIG. 1 will be described again as an example. For route management, the links between routers are handled as a bundle, and the representative link is used for route management.

Reference numerals 12a to 12i denote representative links (link1 ^{* to} LINK9 ^* ) corresponding to the links 11a to 11i in FIG. 1, and the hierarchical routes 32a and 32b are for managing the route in the hierarchical distributed NMS. However, among them, end-to-end routes are expressed hierarchically, such as a lower subnetwork held by an upper layer GMPLS subnetwork, a further lower subnetwork held by the lower subnetwork, or an NE.

In the figure, the hierarchical route_1: 32a has the route of the subnetwork GSN_i30a, the representative link Link5 ^* 12e, and the subnetwork GSN_j30b in the subnetwork TOP_GSN30d. The router LER1: 20a, the representative link Link1 ^* 12a, and the router LSR1: 20b , Representative link Link2 ^* 12c and router LSR2: 20d, and within GSN_j30b, router LSR4: 20f, representative link Link6 ^* 12g, and router LER3: 20h. On the other hand, the hierarchy route_2: 32b has a route of the subnetwork GSN_i30a, the representative link Link8 ^* 12f, and the subnetwork GSN_k30c in the subnetwork TOP_GSN30d. The router LER1: 20a, the representative link Link1 ^* 12a, the router LSR1: 20b, It has a route of the representative link Link3 ^* 12d and the router LSR3: 20e, and has a route of the router LSR5: 20g, the representative link Link9 ^* 12i, and the router LER5: 20j in the GSN_k30c.

FIG. 3 shows a sequence for setting a path on the hierarchical route_1 in FIG. 2 on the GMPLS network using the hierarchical NMS.
The manager system 40 makes a setupRoute request that is a routing request to the smallest GMPLS sub-NMS 30d including the start point and end point routers of the path to be set (1). The GMPLS sub NMS 30d that has received this request determines a route in cooperation between the sub NMSs (30a, 30b, 30d) in the hierarchical distributed NMS (2). This process is described in detail in FIG. Then, this result is returned to the manager system as a reply of setupRoute in the form of the hierarchical route (HR) of FIG. 2 (3).

  Next, the manager system 40 makes a path setting request to the originating router 10a by explicitly specifying a route based on the result of this HR (4). At this time, a route can be set at the router level, or a route can be designated at the HR subnetwork level, and the route at the router level can be left to autonomous distribution of the router.

The manager system 40 confirms by Reply that the path setting request has been made normally (5). This Reply actually returns the link used at the time of setting the path and the label used by the link connection in the case of GMPLS.
The manager system 40 creates a managed object group for managing the path to be set next, and therefore, the setupTrail is set for the NE management system (20a, 20b, 20d, 20f, 20h) corresponding to the router through which the created path passes. Each request is sent (6). As an argument at that time, there are a label for label switching in the router used for path setting and an HR. The representative link of HR is replaced with a link that is actually used at this time.

  Upon receiving the request, the NE management system creates a cross connector (XC) managed object (MO) (23a to 23c in FIG. 1) that manages switching in the router, and termination points (TP) MO at both ends thereof ( 7) The result is transmitted to the upper GMPLS sub NMS (30a, 30b) (8). At that time, HR, XC, and TP are assigned as arguments. The GMPLS sub-NMS confirms the order of the XC received from the lower level in the HR, and holds the permutation of the lower level XC as its component when creating the corresponding sub-network connection object (SNC, 31a, 31b in FIG. 1). To do. A link connection (LC) object (22b and 22d in FIG. 1) is created in the link described in the corresponding HR (9).

  Next, the sub NMSs 30a and 30b transmit the result to the upper sub NMS 30d (10). At that time, HR, SNC, and TP are assigned as arguments. On the other hand, the upper sub NMS 30d similarly creates the MO (11), but holds the permutation (31a, 31b in FIG. 1) of the lower SNC as the connection of the SNC (31c in FIG. 1) with reference to HR. Also, LC (21e in FIG. 1) is created in the link indicated by HR. Since the end-to-end connection of the user corresponds to the SNC that the user has, a trail object is created.

Finally, the sub NMS 30d returns a reply to setupTrail with Trail as an argument (12).
The feature here is that the manager system 40 can request the routing processing request (1) and the management object creation processing request (6) as separate processing from the hierarchical distributed NMS. If it is fast enough, the routing load can be reduced.

FIG. 4 shows an example of how to apply a constraint condition for each subnetwork when performing restricted routing in the hierarchical distributed NMS of this embodiment.
The manager system 40 can set routing restrictions for each subnetwork using the profile setting files 41a and 41b. It is possible to set a plurality of profiles in one subnetwork by using a plurality of profile files.

The profile setting file_1: 41a is applied to the TOP_GSN 30d, and this is specified by setting the GSNId to the TOP_GSN 30d. profileId is an ID of the profile setting file, and is Profile_1 in this example. routingOption describes a constraint condition applied to TOP_GSN 30d. excluded has a condition for routing so as not to pass through Link5 ^{* 12e} . excluded has a condition for routing so as not to pass through GSN_k30c. Preferred has a condition that it is desirable to pass through Link8 ^* 12f.

Here, what should be specified is that the object subject to the restriction of TOP_GSN 30d is an object held by the sub NMS (for example, Link5 ^* 12e, Link8 ^* 12f) or a one-step layer is low (for example, GSN_i30a, GSN_j30b, GSN_k30c). The router groups 20a to 20j are not subject to constraint conditions because the subordinate NMSs manage them.

On the other hand, the profile setting file_2: 41b is applied to GSN_j30b. Mandatory has a condition for routing so that it always passes through Link 6 ^* 12g. Excluded has a condition for routing so as not to pass LER 4: 20i.

FIG. 5 shows a hierarchical route extraction method based on cooperation between sub-NMSs within the hierarchical distributed NMS of this embodiment.
The GMPLS sub NMS that has received the setupRoute request (1) from the manager system 40 starts and ends the subnetwork (or router) having the NE management system at the start point and the subnetwork (or router) having the NE management system at the end point. All the routes possessed by are extracted (step A1). In the NE designation request from the manager system, information on the subnetwork including the NE is designated in a hierarchical structure, so that each subnetwork can determine the subnetwork to which the designated NE belongs.

  Next, in the case where the manager system 40 designates the profile file extracted from step A1, all routes not including the Mandatory element and routes including the Exclude element are excluded (Step A2). Here, the number of remaining routes is checked (step A3). If there is no route (NO in step A3), a “No Resource” exception notification is returned to the manager system. On the other hand, when there are two or more routes, the number of Preferred elements of the routes is compared, and a route including many Preferred elements is extracted (Step A4). If the route is not uniquely determined in the process up to step A4, a route with a lower cost is selected by comparing the sum of the link costs constituting the route (step A5).

  If there is a lower GMPLS sub-NMS (YES in step A6), the NE management system at both ends of the component of the route passing through the sub-NMS is specified to request a route creation request. The NE management system can be derived from having a pointer to the NE management system to be connected as a link attribute of the host system.

  The hierarchical route obtained as a result of repeating the processes of Step A1 to Step A6 until there is no lower sub NMS is the hierarchical route (HR) format that the sub NMS that has received the setupRoute request from the manager system 40 sends to the manager system 40 Send with. Then, the manager system 40 requests the start router to set a path by specifying a route ((4) in FIG. 3).

  With this method, Excluded, Mandatory, and Preferred routing restrictions can be set with higher priority than the sum of the link costs. Further, since the total link cost of the route in step A5 is sorted in advance in the order of cost when the route list is created, it is not necessary to run Dijkstra's algorithm when setting the route.

In many cases, there is no constraint condition, and only the link cost is routed. In this case, since a route with a minimum cost is selected in advance, the delay due to routing can be minimized as in the case of static routing.
FIGS. 6 to 8 each show a method for creating a route list of the population extracted in step A1 of FIG.

  FIG. 6 shows a cost-minimum route when a sub-network management system that manages N (N is an integer of 2 or more) nodes receives a route list creation request with route extraction conditions specified. An example of extracting the next optimum route excluding the optimum route from the node through which is passed is shown.

  The subnetwork management system first extracts an NE (NE management system) or SN (subnetwork management system) as a starting point (step B1). If there is no starting point NE / SN for which the “starting point already calculated” flag is not set (NO in step B2), the algorithm ends. On the other hand, if even one exists (YES in step B2), the Dijkstra algorithm runs from the starting point NE / SN selected in step B1, and the shortest route (route) from the starting point to another NE / SN. (Step B3), and the termination NE / SN of one route is extracted from the obtained plurality of routes (step B4).

  Here, if there is no end point NE / SN for which the “calculated” flag is not set (NO in step B5), the “start point calculated” flag is set in the NE / SN of the starting point selected in step B1. Then, the “calculated” flag of the other NE / SN is canceled (step B6). On the other hand, if there is an end point NE / SN for which the “calculated” flag is not set (YES in step B5), a section representative link between routers not targeted by Dijkstra's algorithm in step B3 is selected ( Step B7). If such a link does not exist (NO in step B8), the “calculated” flag is set in the target NE / SN, and the source NE / SN is set on the route selected in step B3. The next NE / SN is selected (step B9). Then, it is determined whether the NE / SN selected in step B9 is other than “calculated” (step B10). If it is “calculated” (NO in step B10), the process proceeds to step B4 and the next end point NE is determined. Select / SN. On the other hand, if it is not “calculated” (YES in step B10), the NE / SN is selected, and the process proceeds to step B7.

  If there is a section representative link (YES in step B8), only the section representative link that satisfies the condition of step B7 (all that satisfy the condition) is retained and the Dijkstra algorithm is run from the NE / SN. (Step B11). Then, a route obtained by adding the route obtained in step B11 ahead of the route from the starting point selected in step B1 to the NE / SN is selected as a route list candidate of the sub-NMS, and the route list designated by the manager system 40 If the conditions (allowable cost (%) for the cost of the optimum route, number of hops) are satisfied, this candidate is added to the route list in the sub-NMS (step B12). Thereafter, the process proceeds to step B9.

The processing from step B1 to step B3 is performed N times because the number of nodes is N. In addition, since the process from step B4 to step B7 is looped several times for the node passing through the optimum route, the process is performed a maximum of N times. Dijkstra's calculation amount is O (L log (N)), where L is the number of links representing the section, so this calculation amount is O (N ² L log (N)).

  FIG. 7 shows a case where a subnetwork management system managing N nodes and L (L is an integer of 1 or more) bidirectional links receives a route list creation request with route extraction conditions specified. In the following, an example is shown in which a link other than a cost minimum route is specified from a node passing through a cost minimum route, and a cost minimum route passing through the link is extracted.

  The subnetwork management system first extracts an NE (NE management system) or SN (subnetwork management system) as a starting point (step C1). If there is no starting point NE / SN for which the “starting point already calculated” flag is not set (NO in step C2), the algorithm ends. On the other hand, if even one exists (YES in step C2), the Dijkstra algorithm runs from the starting point NE / SN selected in step C1, and the shortest route (route) from the starting point to another NE / SN. (Step C3), and the termination NE / SN of one route is extracted from the obtained plurality of routes (step C4).

  Here, if there is no end point NE / SN for which the “calculated” flag is not set (NO in step C5), the “start point calculated” flag is set in the NE / SN of the starting point selected in step C1. Set and cancel the “calculated” flag of the other NE / SN (step C6). On the other hand, when there is an end point NE / SN for which the “calculated” flag is not set (YES in step C5), the section representative link from the end point NE / SN that is not targeted by the Dijkstra algorithm in step C3. Is selected (step C7). If such a link does not exist (NO in step C8), a “calculated” flag is set in the target NE / SN, and 1 is set to the starting NE / SN on the route selected in step C3. The next NE / SN is selected (step C9). Then, it is determined whether the NE / SN selected in step C9 is other than “calculated” (step C10). If it is “calculated” (NO in step C10), the process proceeds to step C4, and another end point is selected. select. On the other hand, when it is not “calculated” (YES in step C10), the process proceeds to step C7.

  If a section representative link exists (YES in step C8), the Dijkstra algorithm is run from the NE / SN assuming that only one section representative link that satisfies the condition of step C7 is held (step C11). Then, the route obtained by adding the route obtained in step C11 to the destination from the origin selected in step C1 to the NE / SN is selected as a sub-NMS route list, and the route list designated by the manager system 40 If the condition (allowable cost (%) for the cost of the optimum route, number of hops) is satisfied, this candidate is added to the route list in the sub-NMS (step C12). Thereafter, the “calculated” flag is set to the section representative link selected in step C7 (step C13), and the process proceeds to step C7.

The processes in steps C1 to C3 are performed N times because the number of nodes is N. In addition, since the processing of step C4 to step C9 is looped several times for the representative link extending from the node passing through the optimum route, the processing is performed a maximum of L times. Dijkstra's calculation amount is O (L log (N)) where L is the number of links representing the section, and this calculation amount is O (NL ² log (N)).

  FIG. 8 visually shows the route list selected in FIG. 6 and FIG. It is assumed that 10k to 10t is the shortest path from the 10k NE selected by Dijkstra's algorithm to the 10t NE. For example, 11j, 11k, etc. derived from a 10k NE are links other than the shortest path.

  In the algorithm of FIG. 6, assuming that there are links (11j, 11k, etc.) excluding the links that have passed through the shortest path from 10k to 10t, the Dijkstra algorithm is run again in order from the end point 10t. After running the Dijkstra algorithm up to 10k, the end point other than 10t is selected and the same operation is performed. However, when the “calculated” NE has been reached, the next end point is performed. After performing this process for all end points, the next is performed by selecting a start point other than 10k. Then, when this process is performed for all starting points, the process ends. It should be noted that a new route list is obtained by adding a route from a node to an end point obtained by Dijkstra to a route from the starting point to the node. At that time, if the route cost (shortest route ratio) and the number of hops are larger than the limit, the route is removed from the list.

  On the other hand, in the algorithm of FIG. 7, the Dijkstra algorithm is run in order from the end point 10t, assuming that there is only that link for each link excluding the link that has passed through the shortest path from 10k to 10t. When Dijkstra is run for all links of 10t, the same processing is performed up to 10k, such as 10s and 10r. However, when the “calculated” NE has been reached, the next end point is performed. After performing this process for all end points, the next is performed by selecting a start point other than 10k. Then, when this process is performed for all starting points, the process ends. As in the algorithm of FIG. 6, the point to be noted is that a route obtained from Dijkstra from a certain node to the end point is added to the route from the starting point to that node to form a new route list. . At that time, if the route cost (shortest route ratio) and the number of hops are larger than the limit, the route is removed from the list.

  The route list creation in FIGS. 6 and 7 needs to be periodically performed in each subnetwork. This is because the link cost is changed each time it is used. However, this processing is not performed each time routing in FIG. 5, and runs as a separate thread from the routing processing. Therefore, it is not necessary to run the Dijkstra algorithm every time routing is performed, leading to a reduction in delay due to routing.

  FIG. 9 is an example of the present embodiment for avoiding a failure in path setting due to a problem that the optical wavelength cannot be exchanged (shown in FIG. 12 above). In the present embodiment, when the first path setting (route: 108 → 501 → 302) from the source router 108 to the destination router 302 fails in the path setting request ((4) in FIG. 3), The sub-network is notified, and the second route candidate (108 → 202 → 302) having the second smallest cost of the sub-network is notified. By repeating this process, the path setting block rate due to the wavelength capability of the router can be kept low.

  As described above, according to the present embodiment, a list of routes between the starting point and the ending point is maintained, and by providing means for extracting the route that satisfies the constraints and minimizes the cost, the link of the router The need for state exchange can be eliminated, and the bandwidth load for link state exchange can be eliminated. Also, since the sub-NMS in units of sub-networks has the same information between routers, it is possible to reduce the absolute amount of information. Since the routing candidates are calculated in advance in another thread, the delay can be minimized during routing.

  Further, the problem that the path setting is blocked due to the problem of router optical wavelength switching capability can be solved by the NMS proposing a plurality of route candidates in order of cost. Further, by selecting constraint-based routing from a route list that holds Mandatory and Preferred conditions in advance, it is possible to reflect them before cost conditions.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

Path routing management configuration diagram of hierarchical distributed network management system according to an embodiment of the present invention The figure which shows the route corresponding to the hierarchy route example used in the embodiment Sequence chart for creating a management object for path setting and path management in the network management system of the embodiment FIG. 3 is a diagram showing an example of a profile setting file used for setting a routing restriction condition in the network management system of the embodiment. Routing flowchart in the network management system of the embodiment Flow chart of route list creation (maximum N ² pieces) in the network management system of the embodiment Flowchart of route list creation (maximum NL) in the network management system of the embodiment Configuration diagram of a route selected in the route list in the network management system of the embodiment The block diagram which shows the technique which solves the problem that the optical wavelength switching capability is a problem in the network management system of the embodiment, and a path cannot be set Configuration diagram showing exchange of link state information in the same area in the conventional method [OSPF] Configuration diagram showing the exchange of link state information between multiple areas in the conventional method Configuration diagram of the problem that path setting is blocked due to the optical wavelength switching capability of the conventional method

Explanation of symbols

  10a to 10j ... router, 11a to 11i ... inter-router link, 20a to 20j ... network element management system, 21a to 21i ... link management object, 22a to 22d ... link connection management object, 23a to 23c ... cross connection management object, 30a ˜30d ... Subnetwork management system, 31a-31c ... Subnetwork connection management object, 40 ... Manager system.

Claims (3)

List holding means for holding a list of routes between a starting point and an ending point that can be considered in advance for all nodes under management, and a path setting request in which a starting point, an ending point, and routing constraint conditions are specified, and the list holding means A sub-network management system having path setting means for extracting and returning an appropriate route that satisfies the routing constraint condition from the list held in the hierarchy, and is arranged in a hierarchically distributed manner, and cooperates between the sub-network management systems In a network management system that manages path routing,
Each of the subnetwork management systems includes
Receiving a request for creating the list in which route extraction conditions are specified, and extracting each optimum route with the lowest cost between the starting point and the ending point that can be considered in advance, and for each node passing through each extracted optimum route , The route from the node to the other node at the lowest cost through any link not adopted in the optimum route derived from the node is added to the node from the starting point of the optimum route. A network management system comprising: a list creation unit that creates a list of routes that are extracted within a range satisfying the route extraction condition and are held by the list holding unit. List holding means for holding a list of routes between a starting point and an ending point that can be considered in advance for all nodes under management, and a path setting request in which a starting point, an ending point, and routing constraint conditions are specified, and the list holding means A sub-network management system having path setting means for extracting and returning an appropriate route that satisfies the routing constraint condition from the list held in the hierarchy, and is arranged in a hierarchically distributed manner, and cooperates between the sub-network management systems In a network management system that manages path routing,
Each of the subnetwork management systems includes
Receiving a request for creating the list in which route extraction conditions are specified, and extracting each optimum route with the lowest cost between the starting point and the ending point that can be considered in advance, and for each node passing through each extracted optimum route For each link that is not adopted in the optimum route derived from that node, a route from that node to the other node through the link to the other node at the lowest cost is added from the origin of the optimum route to the node thereafter. A network management system comprising: a list creation unit that extracts a sub-route within a range that satisfies the route extraction condition and creates a list of routes to be held by the list holding unit.   3. The list creation unit according to claim 1, wherein the list creation unit accepts a route cost and the number of hops as designation of the route extraction condition, and extracts a sub-route in which the designated route cost and the number of hops are within a limit. Network management system.

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